Originally described as a species of Gerbillus (Gerbillinae), subsequently treated as a species of Aethomys (G. M. Allen, 1939), Thallomys (Ellerman, 1941) or Rattus in subgenus Praomys (Ellerman et al., 1953). There is appreciable variation in body size and pelage coloration among geographic samples, but past systematic studies do not recognize subspecies or significant clinal patterns of variation (Chimimba, 1998; Chimimba et al., 1999). A recent intraspecific morphometric analysis across a more comprehensive geographic region in southern Africa suggested recognition of four subspecies (Chimimba, 2001a) in which distributional limits coincide with major phytogeographical zones. Integrity of these subspecific units, however, requires independent testing with molecular data. Non-geographic variation due to sex and age reported by Chimimba and Dippenaar (1994). Of all the species of either Micaelamys or even Aethomys, M. namaquensis has the most extensive geographic distribution and is sympatric with all the other species of Aethomys and Micaelamys occurring in the Southern African Subregion (Chimimba et al., 1999). Reviewed by Meester et al. (1986), Skinner and Smithers (1990), Chimimba (1998), Chimimba et al.(1999), and de Graaff (1997v).